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UNIVERSITY OF ILLINOIS

Agricultural Experiment Station

BULLETIN NO. 116

ON THE LIFE HISTORY, HABITS,
AND ECONOMIC RELATIONS OF THE WHITE-
GRUBS AND MAY-BEETLES

BY S. A. FORBES
STATE ENTOMOLOGIST

URBANA, ILLINOIS, AUGUST, 1907

CONTENTS OF BULLETIN No. 116.

Introduction: Subject a difficult and complicated one 447

The economic species 448

Ivife histories of the injurious species 449

Lachnosterna at lights and on trees in comparison 451

Variation of numbers in different localities and years 452

Food and feeding habits of the species 454

Results of feeding experiments with May-beetles {Lach-
nosterna} 455

Comparative collections of Lachnosterna from food plants,

Urbana, 1906 456

Movements of migration and dispersal 457

Habits of reproduction 462

Captures of Lachnosterna at light-traps, open fields,

Urbana, 1906 463

Collections of Lachnosterna from trees, Urbana 1906 464

Extract from breeding cage report 465

Relations to weather 466

Modes and places of hibernation ; 467

Principal enemies 468

Swine 468

Crows and blackbirds 468

The common grub wasp ( Tiphia) 469

Miscellaneous insect enemies 472

Relation to soil and subsoil 476

Relation to agricultural management 477

Injuries to crops 477

Prevention and remedy 478

ON THE LIFE HISTORY, HABITS, AND ECONOMIC RE-
LATIONS OF THE WHITE-GRUBS AND MAY-
BEETLES (LACHNOSTHRNA}.

The insects generally known as white-grubs are the young, or
larvae, of the large brown beetles commonly called "June-bugs" or
May-beetles. For a practical knowledge of these destructive insects
it is necessary that we should know the various species of them
which do serious injury to agricultural and to horticultural crops;
the life histories of all these species ; their relative numbers in dif-
ferent parts of the state in different years and in different periods
of years; their food, both as grubs and as adult beetles, including
their common preferences where several kinds of food are available
to them; their significant habits, especially those of reproduction;
their relations to variety of weather and to seasonal change ; their
modes, times, and places of hibernation; the range of their daily
movements and of their movements of migration and dispersal;
their enemies, their diseases — especially those of a contagious char-
acter, and the other natural checks on their multiplication; their
relation to varieties of soil, to its physical condition, its moisture,
and its exposure to the sun ; their relation to varieties of the subsoil
also ; the effects on their continuance and increase, of various agri-
cultural operations and kinds of farm management ; and their own
effects, under varying conditions, on the several kinds of crops sub-
ject to injury by them. Finally, the whole field of preventive and
remedial measures of a more or less artificial character must be
thoroughly explored, including the results of practical experiments
on the scale of actual farm management.

The subject is made especially difficult and complicated by sev-
eral facts and circumstances. There are many species of these
insects recognizable in the beetle stage but seemingly not distinguish-
able as larvae ; hence one frequently can not tell what kind of grub
he is dealing with until he has reared specimens to the adult. The
life history of these insects has a prolonged cycle, probably of three
years, but just how many is not definitely known, and life histories
can be completed only by keeping specimens alive, under more or
less artificial conditions, for this entire time. The various species
differ sufficiently in certain parts of their life histories to make it
necessary to follow each out separately; and it is not impossible
that important differences may be found clue to differences in lati-

447

448 BULLETIN No. 116. . [August,

tude and climate, between northern and southern Illinois; hence
each species must be studied in different parts of the state. The
most important species — that is the most abundant ones — are not
the same in all parts of Illinois, and the relative importance of the
various species must be made out for each region separately. The
unexplained sudden disappearance, several times noticed by us, of
nearly the whole grub population of badly infested fields before
their transformation to the pupa, suggests the occurrence among
these insects of contagious diseases — a supposition borne out by sev-
eral field and insectary observations ; and the whole subject of their
bacterial and other fungus parasites consequently invites attention.
The enormous effect of the rapid multiplication, under favorable
conditions, of certain insect parasites — a hymenopterous enemy,
Tiphia inornata, especially — requires a critical and complete study
of the life history of these parasitic insects also, especially as there
is some probability that we shall be able to increase their efficiency
by artificial measures.

No one has heretofore undertaken to work out to a finish this
difficult but highly important economic problem, and our present
knowledge of the white-grubs is a patchwork of fragments, contrib-
uted by a considerable number of observers working on various
species and in different parts of the country. The nearest approach
thus far made to a continuous investigation of the subject was car-
ried on in this office in the years of 1886-1890, and its results were
published in 1891 in Volume III. of "Insect Life."*

They were also incorporated, with some later studies, in the
Eighteenth Report of the Illinois State Entomologist, printed in
1894. In the year 1906 I finally began what I now hope may prove
to be a steady and comprehensive study of this problem for the
state of Illinois ; and I have now to report some of the first results
of this work, which I have incorporated, however, with other data
and conclusions in a way to give us a fairly full synopsis of the
present state of our knowledge, and a clear view, consequently, of
its deficiencies.

THE ECONOMIC SPECIES.

The kinds of white-grubs common enough in Illinois to attract
attention because of their injuries, belong, so far as we now know, to
nine species, although it is likely that this list would be longer if the
injurious grubs of southern Illinois were as well known to us as
those of the central part of the state. Besides these nine injurious

*"On the Life History of the White-grubs." By S. A. Forbes. Insect Life, Vol. III., No.
5, pp. 239-245.

1907.'} WHITE-GRUBS AND MAY- BEETLES. 419

grubs, there are three other very abundant kinds which resemble
closely the injurious species, although they are themselves harmless
in the grub stage.

Eight of the species known to be injurious belong to the genus
Lachnosterna and one to the genus Cyclocephala. Of the abundant
but harmless grubs, one, frequently called the muck-worm because it
lives in stable manure, is known to science as Ligyrus relictus ; an-
other, called the carrot-beetle in the adult stage, is L. gibbosa ; and
the third is the larva of the green June-bug of southern Illinois and
of the Southern States generally, known in the beetle stage as Allo-
rhina nitida. All the last three species are injurious as beetles, but
only one of them, the larva of the carrot-beetle, is at all injurious as
a grub, and then only slightly or occasionally so. The eight species
of Lachnosterna known to be injurious in Illinois are L. fusca,
rugosa, inversa, implicita, gibbosa, tristis, ilicis, and hirticula ; and
the injurious Cyclocephala is C. immaculata.

Life Histories of the Injurious Species. — The life histories of
the white-grubs of the genus Lachnosterna are very imperfectly
known, especially as to the length of time required for the growth
and development of a complete generation. The literature of the
subject records, in fact, but a single case in which a Lachnosterna
has been reared from the egg to the adult. An egg of L. arcuata
laid in Washington about June 8, 1893, hatched in approximately
eleven days, and changed to the pupa August 8, 1895, and to the
beetle twenty-three days later.* As this beetle would doubtless have
hibernated in the earth to emerge the following spring and lay its
eggs in June, the entire period from the egg to the egg again was
three years. This is the length of the life cycle which has com-
monly been inferred, from circumstantial evidence, for our species
of Lachnosterna generally. It is worthy of note, however, that Melo-
lontha vulgaris, the European white-grub nearest in classification
and habits to our American species, has been found, according to
Xavier Raspail, to have, in France, a period of three or four years
—the shorter period if the years are moist and the longer one if
they are dry.f In Germany, on the other hand, this species has a
four-year period at the north and a three-year period at the south,
with various occasional exceptions and irregularities of appearance;
and a related species, M. hippocastani, has a five-year period in north
Germany. Our American species of Lachnosterna will probably be
found to present similar variations of life history.

*"BioIog-ir Notes on the May-beetle Lar.hnosterna arcuata Sm." By F. H. Chittenden.
Bull. 19, N. S., Div. Ent., U. S. Dept. Atrr., p. 77.

tBull.de la Soc. Zool. de France, 1891, p. 271; Mem.de la Soc. Zool. de France, 1893, T. VI.,
p. 202.

450 BULLETIN No. 116. [August,

Whatever the length of life in the grub stage, all our most
abundant species of Lachnosterna begin to pupate in June or July
in central Illinois, and begin to change to the beetle in August or
September, remaining, with rare or doubtful individual exceptions,
under ground in this stage until the following March, April, or
May. They then emerge from their winter quarters, feed on the
leaves of various trees, and pair and lay their eggs in the earth in
June and July. An exception should perhaps be made, provisionally,
of Z-. tristis, concerning which my records are unusually imperfect,
agreeing, so far as they go, with those of the other species of our
list, but stopping- short before the middle of June. That is, we have
an abundance of the beetles collected from the latter part of March
through April and May and into early June, most frequently, how-
ever, in May, but have no collections in any stage at any date later
than June 5. Four of our lots of tristis, collected in March and
April, were beetles taken from the earth, which must have trans-
formed the preceding summer or fall.

Pupae of the above species have been taken by us from their
underground cells only in June, July, August, and September, and
the adult beetles have been found under ground in the cells where
they originated, in August, September, October, and November, and
again in April and early May. Adults of various species have been
seen pairing in May, and in one case in June, and eggs of seven of
these species — tristis being omitted — have been secured in June and
July, much the greater part of them in the former month. So far
as my rather scanty records go, the eggs may be expected to hatch
from ten days to four weeks from the time of deposit. My dates
for the hatching of eggs of known species are, for inversa, June 23
and July n ; for fuse a, June 27; for implicit a, July 16, 21, and 24,
and August 7 ; and for hirticula, July 7.

From this it will appear that white-grubs found in the earth
beyond the middle of September will not change to the beetle that
year, but, barring destruction by parasites and other fatal accidents,
may be expected to pass the winter as grubs and to continue in
that stage at least until the following June. This is a point of
special economic interest, since the owner of infested fields needs to
know whether the grubs in the ground during the latter part of the
season will continue there in dangerous numbers during the follow-
ing spring, or whether he may expect relief from their injuries by
reason of their change to the beetle.

The data of my collections, when taken in the aggregate for
several years, give little indication of any fixed order of succession

1907.]

WHITE-GRUBS AND MAY-BEETLES.

451

in the first appearance of the different species of Lachnosterna in
spring1. Inversa, fusca, rugosa, hirticula, and tristis have all been
taken by us in the- later days of March, and gibbosa on April 6.
Implicita and ilicis have made their first appearances about a month
later than the average, but, although implicita is sometimes excess-
ively abundant, these two species have been much less frequently
taken by us than the others, and the record might have been differ-
ent if the collections made had been equally numerous. The dates
of last occurrence are also nearly the same for these species, and
their periods of greatest abundance do not vary greatly.

Fusca, however, commonly appears in large numbers at electric
lights about a week earlier than the other species, and gibbosa is
about as much later than the others — a fortnight later than fusca.
Our records of egg-laying are substantially the same for all the
seven species covered by them. So far, consequently, as the mere
period of adult activity is concerned, these insects are virtually one
species, and we must look to other facts and conditions for any spe-
cific distinctions of habit or agricultural relation.

I find that the data of the relative abundance and dates of emer-
gence of the various species derived from electric-light collections
disagree widely with the data of collections made from the food
plants of the beetles at the same time. Apparently some of the
species are more strongly attracted to lights than others. In 1891,
and again in 1906, collections were made at Urbana from trees and
from lights during the greater part of the active period of the May-
beetles, with the results shown in the following table .

LACHNOSTERNA AT LIGHTS AND ON TREES, IN COMPARISON. URBANA.

18

91

19

06

Lights

Trees

Lights

Trees

No. Specimens

1874

836

142

3484

Iv. gibbosa

.02

.02

.00

03

Iv. inversa

.76

.32

.54

00

L. dubia

•00

.00

02

00

L/. fusca

05

.23

00

01

Iv. rugosa

.00

.00

24

06

Iv. implicita

.00

.00

15

72

Iv. hirticula

10

42

03

07

L/. ilicis

.00

00

02

10

Iv. tristis

\ .07

.00

.00

.01

452 BULLETIN No. 116. [August,

In 1891, when 1,874 specimens were taken from lights and 836
from trees, the dominant species at lights was inversa (76 per cent.),
hirticula, tristis, and fusca following with ratios of 10 per cent., 7
per cent., and 5 per cent, respectively. The dominant species from
trees, on the other hand, were hirticula (42 per cent.), inversa (32
per cent.), and fusca (23 per cent.), the only other species being
gibbosa (2 per cent.). The results for 1906, when 142 specimens
were taken at lights and 3,484 at trees, were equally discordant.
The leading species at lights this year was inversa (54 per cent.),
rugosa and implicita following with 24 per cent, and 15 per cent,
respectively; while the leading species in trees was implicita (72
per cent.), followed by ilicis and rugosa, 10 per cent, and 6 per cent,
respectively.

Variation of Numbers in Different Localities and Years. — The
numbers of the several species vary greatly from year to year in the
same locality, and in different localities during the same season. It
consequently happens that the dominant species in a locality may be
different in successive years, and that the dominant species in one
locality may be different from that in another, within the same year.
Collections have not been made on a large enough scale or in suf-
ficiently continuous series to enable us to exhibit these differences in
any detail, but the following may serve as illustrations : —

Collections made at a street-lamp in Maywood, near Chicago, by
O. S. Westcott,* on seventeen nights from May 9 to June 14, 1887,
contained 798 specimens of fusca and 313 of gibbosa — fusca pre-
dominating in a ratio of more than 2*/£ to i ; and collections made
the following year at the same place by the same person, on seven-
teen nights between June 2 and July 2, gave 73 specimens of fusca
•and 1,836 of gibbosa — gibbosa now predominating in a ratio of
25 to I. The difference in the collection period of the two years
was due to the difference in the weather of the spring, which was
backward and stormy in 1888. If we compare the collections of the
same periods for these two years — June 9 to 14 in 1887, and June 9
to 13 in 1888 — we have 96 specimens of fusca to 82 of gibbosa in
1887, and 29 of fusca to 1,020 of gibbosa in 1888.

A similar comparison may be made between the contents of fre-
quent collections from trees made at Urbana through the whole
period of activity of the May-beetles in 1891 and again in 1906 — 836
specimens in the former year and 3,484 in the latter. (See table
on p. 451.) In the collections of 1891 the dominant species were
hirticula (42 per cent.), inversa (32 per cent.), and fusca (23 per

*"Eotomologica Americana, Nov., 1888, Vol. IV., p. 155.

1907.] WHITE-GRUBS AND MAY-BEETLES. 453

cent.), the only other species represented being gibbosa (2 per cent.).
In 1906, on the other hand, the dominant species was implicita (72
per cent.), the remaining species, mentioned in the order of their
abundance, being ilicis (10 per cent.), hirticula (7 per cent.), rugosa
(6 per cent.), gibbosa (3 per cent.), and fusca and tristis (each I
per cent.). This latter comparison is vitiated, however, by the fact
that the collections were made from different kinds of trees, those of
1891 mainly from butternuts and hickories, and those of 1906 from
poplars, willows, elms, and oaks, — another example of the fragmen-
tary and disjointed character of the data now available for a study
of this subject.

It so happens that extensive collections of May-beetles were
made in 1888 both in Cook county, 111., by Westcott, and in the Dis-
trict of Columbia by J. B. Smith,* and a comparison of the relative
numbers of the dominant species in these two widely separate locali-
ties would be possible by their means if it were not for the fact that
Westcott's specimens were all taken at lights and Smith's were ob-
tained from trees and shrubs. As already shown, collections are
not comparable when made in these different ways.

Much more nearly equivalent collections were made in 1906 by
two assistants of my office, one working at Urbana, in Champaign
county, between May 26 and June 23, and the other at Elliott, in
Ford county, between May 23 and June 5, the first collecting at
lights scattered through fields of grass a total of 142 specimens in
ten nights, and the second obtaining at a single light in a large corn
field 389 specimens in six nights. At Urbana the dominant species
was inversa (54 per cent.) ; at Elliott it was gibbosa (71 per cent.).
At Urbana gibbosa was not taken in these light-collections, and at
Elliott inversa made but 20 per cent, of all obtained.

A further profitable comparison may be made of data contrib-
uted by Prof. M. V. Slingerland from the product of light-traps
kept in continuous operation at Ithaca, N. Y., during the seasons of
1889 and 1892.1 Four hundred and thirty-eight specimens of
Lachnosterna were taken during the first of these years, and 273
during the second. Fusca was much the most abundant species in
both years, making 76 per cent, of the product of the traps in 1889,
and 90 per cent, in 1892. Dubia was next to fusca in 1889 (15 per
cent.) ; and this species and ilicis, each 4 per cent., were likewise
next to fusca in 1892. The similarity of the records for these two
years is possibly due to a three-year period of the dominant species,

*"Proc. U. S. National Museum, 1888, Vol. II., p. 488.
Canadian Entoniolog-ist, March, 1893, Vol. XXV., p 81.

454 BULLETIN No. 116. [August,

fusca, but, unfortunately, as no comparable collections were made
in the intermediate years, the evidence is not complete. Westcott's
Maywood collections, already referred to, on the other hand, hint at
a two-year period for L. gibbosa. This species predominated over
fusca in 1886, as shown by records made on five nights, from the
26th of May to the ist of June, in a ratio of 3.6 to I, and again in
1888, in a ratio, as already stated, of 25 to i, but was much less
abundant than fusca in the intermediate year.

FOOD AND FEEDING HABITS OF THE SPECIES.

The white-grubs and the May-beetles, larvae and adults of the
same insect species, differ totally in their food and feeding habits,
the grubs eating the roots of various kinds of plants and the beetles
eating the leaves of trees and shrubs. In the absence of any means
of distinguishing the species one from another in the grub stage, no
evidence has been obtained of any special choice, by any of the
species in this stage, among the various elements of the food of
grubs in general. So far as known, all of them may take, with
equal relish, all kinds of food which any one of them will eat. If
the different species of grubs do indeed make definite and varied
choice of food, the fact may be ascertained by breeding to the adult,
for determination, pupae and full-grown grubs obtained in various
situations near or among different kinds of food plants; but there
is at present too little recorded information on this point to permit
us to infer any difference whatever in the choices of our more
abundant species.

The species of beetles themselves, on the other hand, differ con-
siderably, although not sharply and completely, as a rule, in their
choices of food where several kinds are equally accessible to them.
Evidence of these preferences has been obtained by us in three dif-
ferent ways: (i) by experimental feedings with beetles kept in
confinement; (2) by parallel collections of beetles made from dif-
ferent kinds of food plants; and (3) by the dissection of specimens
of various species, made to determine, by an examination of the
contents of their alimentary canals, what kind of vegetation they
have been feeding on. The first method shows what the beetles may
eat under stress of hunger, or perhaps with starvation as a penalty
for refusing what is offered them ; the second shows what the dif-
ferent species actually choose when a choice is open to them; and
the third enables us to determine with certainty what the beetles
have eaten where direct observation is impracticable. The results
of our feeding experiments have been so different from those ob-

1907.}

WHITE-GRUBS AND MAY-BEETLES.

455

tained by making collections from the food plants at night that they
evidently have comparatively little real value. For example, leaves
of Osage orange were offered, without other food, to fusca, inversa,
implicita, ilicis, rugosa, and tristis. They were eaten moderately
by implicita and rugosa, and slightly by fusca, inversa, and ilifis,
but were constantly refused by tristis. On the other hand, extensive
observations made in the field have given us no instance of actual
feeding on this plant in the open air by any of our species, although
it is ever}; where in common use as "a hedge plant.

The following table shows the different kinds of food offered to
Lachnosterna beetles in breeding-cages in 1904 and 1905, and data
as to the readiness with which each sort of leaf was eaten when
but one kind of food was placed in the cage.

RESULTS OF FEEDING EXPERIMENTS WITH
MAY-BEETLES (LACHNOSTERNA)..

-

Gibbosa

Inversa

rt
o
•

3
fc

Rug-osa

Implicita

Hirticula

•
°o

M

Tristis

Average

Carolina Poplar,

(Populus moniliftra) .

1

3

3

3

3

3

3

2

2]62

Willow

_

. 3

3

2

3

_

3

1

2.iO

Oak

2

3

2

2

3

3

2.50

E}lm

3

2

3

2

2

3

3

3

2.62

Apple

1

2

3

3

3

3

3

1

2.37

Box-elder

1

2

3

1

3

2

2

0

1.75

Plum

1

0

3

0

3

3

2

0

1.50

Peach

1

0

1

0

1

1

1

0

.71

White Ash

1

-7

1

1

3

2

1

0

1.57

Tulip tree,

(Liriodendron) . .

0

1

1

0

1

1

0

0

.57

Hedtre . .

_

1

1

2

2

_

1

0

1.40

L/ilac

_

1

2

1

_

1.33

Cherry

1

1

1

1.

Corn

_

2

2

2

2

_

1

0

1.50

Grass. .

_

2

2

2

1

_

1

0

1.60

l=slig'htly eaten, 2 =tnoderately eaten, 3 = freely eaten, 0 = refused to eat, - = not offered.

An attempt was also made to test the general food preferences
of each species by offering several different kinds of food in the cage
at once. Under these conditions, L. fusca, inversa, and implicita
ate most freely of Carolina poplar and willow ; L. ilicis and hirticula
ate most freely of oak, but freely, also, of Carolina poplar and dm ;
and L. tristis ate only oak when that was present. L. rugosa se-
lected poplar and elm, and L. gibbosa, oak and elm.

In 1906, at Urbana, extensive collections were made with equal
care from each of the four different kinds of trees which May-beetles

456

BULLETIN No. 116.

[August,

seemed to prefer as food. The beetles were gathered by shaking
them from the trees at night and picking up those which fell to
the ground.

The following table gives the results of these collections made
at Urbana from Carolina poplar (cotton wood), willow, oak, and
elm, on twenty-six different nights between May 14 and June 28,
1906.

COMPARATIVE COLLECTIONS OF LACHNOSTERNA FROM FOOD
PLANTS. URBANA, 1906.

Species

Poplar

Willow

Oak

Elm

•

No.

Per
cent.

No.

Per
cent.

No.

Per
cent.

No.

Per

cent.

L/. implicita

1456
169

73
39
10

5
2

.58
.85

.72
.85
.04

855

7
6
6
4
1

.34

.07
.13
.03

35

18
1
209

2
317

25

.01

.17
.02
.86

.93
1.00

171
31

4

17
21

.07
.15
.04

.07
.07

L/. mgosa

L/ gibbosa

L/. f usca

L/. hirticnla

L/. ilicis

L/. tristis

Total

1754
.50

879

.25

607
.18

f

244
.07

Per cent, on each tree

From the foregoing table it will be seen that poplar (cotton-
wood) was the favorite food, 50 per cent, of the specimens being
taken from this tree, and that willow follows next with 25 per cent.,
oak with 18 per cent., and elm with 7 per cent., poplar and willow
together yielding 75 per cent, of the insects. Apple leaves were
often eaten freely, but no trees were suitably situated for experimen-
tal field-collecting, and hence no comparative records were made
which included apple. Apple orchards in the southern part of the
state have been reported by assistants as sometimes almost stripped
of their leaves. This was notably so in Jackson county in 1904.
The pecan- and persimmon-trees of southern Illinois often suffer
severely by having their foliage eaten by the beetles.

Certain species of the beetles exhibited marked preferences in
the choice of food. L. hirticula, ilicis, and tristis had a special liking
for oak, the last named being taken from no other tree. L. implicita,
gibbosa, fusca, and ntgosa were most abundant on poplar, rugosa
seeming to avoid oak and willow. Not enough specimens of L,. in-
versa were taken to warrant conclusion's concerning its preferences.

All of the May-beetles taken at lights in the open fields at night
in 1906 at Elliott, Ford county, and at Urbana, Champaign county,
were carefully dissected and the contents of the alimentary canals

1907.] WHITE-GRUBS AND MAY-BEETLES. 45*7

were examined microscopically. Nearly 40 per cent, of all the
May-beetles taken had eaten nothing. This percentage was much
the highest for specimens taken early in the season, 62 per cent., for
example, for those caught before June 6. Probably most of these
empty beetles had just come from the earth and had not yet begun
to feed. Nearly all of those captured in the fields .at lights which
had taken food had eaten the leaves of trees, as was shown by the
presence in their intestines of small pieces of leaves exhibiting the
netted vein-structure and other characteristics of the foliage of the
common trees of the vicinity. Only six specimens of about six hun-
dred dissected, had eaten the leaves of young corn. Five of these
specimens belonged to L. rugosa and the sixth to L. inversa. Four
additional specimens of L. rugosa were taken at Urbana directly
from corn while feeding on it. As these ten beetles represent only
about i^4 Per cent. of the whole number examined, the facts indi-
cated by them are of little economic significance except as going to
show that May-beetles, of these two species at least, emerging in
corn fields at a distance from trees too great to enable them to find
their more ordinary food, may nevertheless subsist on leaves of
corn. The same facts have been shown with reference to blue-grass,
and it seems probable that, in the absence of other food, beetles may
be able to live on the blue-grass of our pastures. With their actual
powers of flight and their strong disposition to assemble in trees at
night, not merely to feed but likewise to copulate, their ability to
feed on grass and corn seems to signify but little. Corn, oats, wheat,
clover, and grass fields were repeatedly examined in both Ford and
Champaign counties with a view to the detection of any injury
which might have been caused by these beetles. Occasionally at
Urbana, and more frequently at Elliott, corn plants were found
which, though uninjured in the evening-, were partially eaten by the
next morning, and, as already mentioned, four May-beetles (Z,.
rugosa) were taken directly from the plants while feeding on them.
Dissection of these specimens showed beyond a doubt that they had
eaten the leaves of corn. Two hundred and sixty-two specimens of
this species were taken in 1906, 169 of them from poplar, 31 from
elm, and 62 from other situations, and only 9 of these had eaten
corn, as biiown by dissection.

MOVEMENTS OE MIGRATION AND DISPERSAL.

As the larvse known as white-grubs never appear above ground
except by accident, and as they are sluggish insects, incapable of
rapid locomotion under ground, each is practically confined, so far as

458 BULLETIN No. 116. [August,

we now know, to the immediate neighborhood of its origin. The
grubs change location slowly as their food is exhausted, and injured
spots in an infested lawn or grain field will gradually enlarge in all
directions, the white-grubs moving outwards into fresh pasturage
as the infested vegetation dies from the destruction of its roots. The
grubs also sometimes gather in from all directions towards a par-
ticularly attractive patch of their food plants ; but there is nothing
to show that they move from place to place by definite underground
migration, or that they cover any considerable distance, such as to
take them from one field to another, during the whole period of their
active larval life.

The May-beetles also seem local in their distribution. Although
very good fliers, they use their wings only to carry them from their
place of origin to the trees and shrubs on which they feed and in
which they copulate at night, and from these to their daytime hid-
ing places, never moving in swarms, so far as known, or migrating
over considerable distances. There is, in short, no evidence of any
migration movement of this insect in any stage or under any cir-
cumstances, but each locality or considerable neighborhood prob-
ably breeds and maintains its own white-grub population year after
year. Their most marked movements are the evening flight of the
beetles to their food plants, and the morning dispersal from trees
to the fields in which the females lay their eggs.

The discovery that certain species, at least, of the May-beetles
may feed, and sometimes do feed to a small extent, on corn and
grass, and the^ consequent conclusion that they may not need con-
venient access to trees for food, raises the important question
whether some of these insects, and possibly certain species of them,
may not live continuously in the fields, feeding on the crop plants
there and laying their eggs in the very places where they themselves
originated. If this is the case, collections made in the fields at max-
i.-.ium distances from trees should give us proof of the fact; and I
consequently arranged, in the spring of 1906, for the systematic use
of lantern traps distributed over an open area of one hundred and
sixty acres on the main farm of the University of Illinois, with trees
of various sorts in a cemetery along one side of this tract, and no
others within less than half a mile from it in any direction. These
traps were ordinary kerosene lanterns, with glass globes, placed
over large tin trays, each containing kerosene to a depth of about
half an inch. These trays were not large enough to secure all the
beetles which flew against the lantern globes, but they nevertheless
gave satisfactory samples of the beetles flying in the field.

1907.}

WHITE-GRUBS AND MAY-BEETLES.

4o9

The accompanying plat shows the crops of this tract and the dis-
tribution of the lantern traps in each. Forty acres were in corn,
seventy acres in grass, thirty acres in clover and alfalfa, and twenty
acres in oats. Two of the lanterns were in corn fields, two in clover

Plat showing Distribution of Light-traps.

Cemetery

Road

Road

New pasture
20 acres

Oats
20 acres

Old pasture
40 acres

Alfalfa
20 acres

• Clover
10 acres

Corn
20 acres

Meadow grass
10 acres

Corn
20 acres

and alfalfa, one in oats, and seven in meadows and pastures of grass.
None were nearer than a quarter of a mile to trees on whose leaves
the May-beetles were feeding at the time, nor farther from them
than three quarters. To avoid attracting beetles from these trees,
each lantern was provided with a tin shade by which its light was
hidden on the side towards the trees nearest to it. These lights were

460 BULLETIN No. 116. [August,

kept burning all night for fourteen nights between May 20 and June
23 inclusive, and were visited at frequent intervals during each of
these nights. The weather was so cold during four nights that the
May-beetles were not flying, and no account is taken of these nights
in this discussion.

The total product of the twelve traps, thus maintained for ten
entire nights, was 142 specimens of May-beetles of the genus Lach-
nostcrna and 25 specimens of Cyclocephala. No account is taken of
the latter because their food habits are very different from those of
Lachnostcrna. The average product of a lantern in one night was
only 1.2 of the true May-beetles (Lachnosterna), and the largest
catch of any one night was 40 specimens on June 18, or 3^3 per light.
The largest collections were made on three nights between June 9
and 1 8 inclusive, these averaging 33 per night, or about 3 to each
trap. The two collections of May, made on the 26th and 3ist of
the month, averaged only 6 beetles per night, or i to each two traps.

A single light-trap of the same kind, exposed at night withoyt a
screen, for ten minutes May 21 and for thirty minutes May 23, close
to willow-trees at the border of this field and near the cemetery
above mentioned, yielded 1 1 May-beetles on the first night and 127 on
the second — seventy times as many taken in ten minutes by one trap
near these trees as were taken at approximately the same date by a
trap exposed all night in the open field. There could be no question,
consequently, that very nearly all the May-beetles of this neighbor-
hood were concentrated in the trees at this time.

New data have been obtained by our collections and observations
of recent years with regard to the nightly movements of the beetles,
and these are thus summarized by Mr. J. A. West, who had charge
of this work for 1906.

"There is a regular migration of beetles from the fields to the
trees in the evening. It takes place in June just about dusk — from a
few minutes before to a few minutes after eight p. m. The move-
ment of the beetles is almost simultaneous from the different fields.
An observer in one field can scarcely move to another and hope to
see the migration. It is usually but a few seconds from the time
its beginning is noticed in one place until a companion observer will
report its commencement perhaps a quarter of a mile away. Beetles
were found rising from the ground in fields of oats, in pasture, old
meadow, clover, alfalfa, and in corn. They were most abundant from
old pasture and least numerous from alfalfa and corn. They were
observed coming from the ground in considerable numbers in oats
and clover fields. The following species are mentioned in the order

1907.] WHITE-GRUBS AND MAY-BEETLES. 461

of their abundance : L. implicita, hirticula, ilicis, and rugosa. The
evening migration occupies not over fifteen or twenty minutes, and
in every instance it seemed completed by 8 : 20 p. m.

"While the evening migration seemed to result in a complete
abandonment of the fields by the beetles, yet the observer may now
and then hear a beetle whirr past in the darkness at any hour of the
night, and light-traps so placed in the open field as not to attract
those from the trees will take specimens in small numbers through-
out the night. The beetles distribute themselves regularly over
large areas when they leave the feeding grounds in the morning.
The following is a record of specimens taken in the fields a quarter
of a mile or more from trees, and apparently coming directly from
them: L. implicita, n, L. hirticula, 5, L. rugosa, 31, — total, 47.

All these specimens were taken by hand, the light-traps not
seeming to attract them.

"The morning movement is very early. It varies considerably,
according to the clearness of the sky. It is so related to the awaken-
ing of the birds that it seems as if the first note of the dick-cissel, or
other early bird, is the signal for the beetles to fly to their hiding
places in the ground. On only two mornings were beetles taken in
June after four o'clock. June 18, a dark cloudy morning, a pair
of L. rugosa were taken at 4 : 25 a. m. while in copulation on a stem
of grass. Ordinarily the movement did not last over fifteen min-
utes and it very rarely continued for twenty minutes. On the morn-
ing of June 7, however, a strong wind was blowing thirteen to four-
teen miles an hour from the south. This greatly retarded the
flight of the beetles which had been feeding on trees to the north of
the fields, and on this morning it began at 3:35 o'clock and con-
tinued until 4:10, when the last beetle seen was taken in flight.

"The following notes show the variation in the time of the
morning movement of the beetles according to the brightness of the
morning and its relation to the awakening of the birds : —

"Morning of June 10, moonlight and very bright. Dick-cissel
heard at 3 : 08 ; meadow-lark at 3 : 15; kingbird at 3 : 20 ; the follow-
ing, in order given, from 3:25-3:35, — prairie-chicken, brown
thrasher, quail, robin, and horned lark. On this morning the beetle-
movement began at 3 : 18 and lasted until 3 : 30.

"Morning of June 18, very cloudy and dark. No bird was heard
until 3 : 40, and the movement of the beetles began at 3 : 45 and was
complete in ten minutes. About 3 : 30 a.m. was the average time for
the first bird note, and 3 : 35-3 : 45 the regulation time for the morn-
ing movement of the beetles."

462 BULLETIN No. 116. [August,

These data are of special importance as showing the time of
night when the beetles are accessible in the trees on which they
feed — a subject important to a discussion of measures of prevention
and remedy.

HABITS OF REPRODUCTION.

With respect to the reproduction of May-beetles, we need to
know at what time of day, in what situations, and especially how
soon after emerging, the sexes pair, and when, where, how soon, and
in what numbers the females deposit their eggs. Our definite infor-
mation as to the pairing of the beetles is not abundant, but is suffi-
cient to show that they pair at night on their food plants. The males
are much more active than the females, — a fact illustrated by their
greater abundance at lights in fields at a distance from trees. In
the product of the light-traps used in 1906, as described in this paper
under "Movements of Migration and Dispersal," pp. 458-460),
the males outnumbered the females about 4 to I, while in collections
made at the same time from trees the number of males was only
39 per cent, of the total number taken. Similar data were given
in my Seventh Report.* It will be seen that it does not follow from
the greater number of females taken on the food plants that females
are actually more numerous than males, but only that the latter are
more widely scattered at night, and more generally on the wing.

It has been noticed by some of the office assistants, and par-
ticularly by Mr. J. A. West, that May-beetles are sometimes very un-
equally numerous in neighboring trees of the same kind, one tree
containing a buzzing multitude while there are comparatively few
on another tree of the same species close by. I have myself once
seen a large tree so full of May-beetles in the evening that the noise
of their movements was like that of a huge swarm of bees, although
the condition of the leaves the following day showed that they had
not resorted to this tree for food. Their assemblage in tree-tops is
evidently in part for breeding purposes, and not wholly for food.

About fifty pairs of these beetles have been taken by us in
copula, all but three of them from trees at night. In one case a pair
of.Z,. rugosa was captured at night by Mr. West from a grass-blade
in a pasture, and two pairs of L. inversa have been seen copulating
in a breeding-cage, also at night. These two pairs had been taken
from earthen cells in the ground October 5, 1905, and transferred to
the insectary, where they at once went into the earth, first appearing
above ground on the ist of the following May. They began to feed

*Eighteenth Rep. State Ent. III., p. 117.

1907.]

WHITE-GRUBS AND MAY- BEETLES.

463

on elm leaves May 17, and paired at midnight May 25. Our ob-
served dates of copulation all fall within the month of May.

The several species of May-beetles may continue active, in a nor-
mal season, from one to two months, reckoning this period from the
first appearance of the earliest specimens to emerge to the final disap-
pearance of the beetles for the year. In our work of 1906 the dates
of first and last appearance of the more abundant species in collec-
tions made regularly near Urbana, at night, from willow, oak, elm,
and cottonwood (Carolina poplar), were as follows: L. implicita,
May 13* and June 28 (46 days) ; L. ilicis, May 21 and June 23
(33 days) ; and L. hirticula, May 23 and June 18 (26 days). In
New York, on the other hand, Professor Slingerland some years
ago obtained L. fusca in his light-traps from May 6 to July 5, 1889,
and from May 26 to June 28, 1892 ; L. dubia from May 8 to July 5,
and from May 30 to June 22 ; and L. ilicis from June I to July 30.

CAPTURES OF LACHNOSTERNA AT LIGHT-TRAPS, OPEN
FIELDS, URBANA, 1906.

Inversa

Implicita

rt

3

3

O

Hirticula

Rug-osa

a>

3

01

u

"d

X

Females

May 26

4

4

o

May 31

6

1

1

5

3

June 2

8

3

5

6

June 4

6

1

3

4

8

6

June 6

2

3

4

1

June 9

18

1

1

2

7

9

25

6

June 15

22

5

24

3

June 18

16

9

15

40

0

June 20

i

0

1

June 23

1

0

1

Total . .

76

21

3

5

34

3

115

27

Collections made only from the food plants commonly show a
more rapid diminution and earlier disappearance of males than of
females. We may take as an example 2517 specimens of L. implicita
collected from trees on twenty-six different nights between May 14
and June 28, 1906. Thirty-nine per cent, of the specimens taken
during the first thirteen days were males and only 15 per cent, of
those taken during the last thirteen days. On the other hand, in
collections made during the same period by means of lantern traps

*The spring was unusually late this year, and Ma3'-beetles did not appear on the wing-
until May 13.

464

BULLETIN No. 116.

[August,

scattered through the open fields, at a distance from the food plants
of the beetles, the ratio of males to females was precisely twice as
great during the last half of the period as during the first. Slinger-
land's data, already referred to, do not support the supposition of
a relatively early death of the males. It seems likely, consequently,
that females may require repeated fertilization, especially as the
eggs are laid gradually, a few at a time.

COLLECTIONS OF LACHNOSTERNA FROM TREES, URBANA, 1906.

Implicita

Fusca

Gihbosa

Rug-osa

Ilicis

Hirticula

Inversa

Tristis

0

V

0)

0

<0

0)

rt

rt

a

~*

ri

a

ri

a

s

n

&

fi

a

g

fi

£

g

n

t)

rt

u

<u

«

V

«

ctf

u

<u

8

fa

«

fa

%

fa

%

fa

8

• fa

E

fa

*

fa

H

fa

May 14. .

59

90

3

1

May 15.. ..

74

95

8

2

May 16. .

27

52

5

3

May 17.. ..

109

200

1

May 21. .

24

23

1

May 22 ...

19

25

10

2

1

May 23. .

193

239

7

7

8

2

3

14

5

2

1

May 24. .

25

26

2

5

1

2

2

May 25.. ..

31

35

May 26.. ..

104

135

5

4

4

1

13

9

3

1

1

1

May 30. .

4

25

6

5

1

2

May 31.. ..

50

108

17

2

28

24

45

21

6

5

June 1.. ..

24

125

4

3

12

6

3

1

June 2. .

45

129

8

8

12

4

June 4. .

14

96

3

19

14

5

16

3

1

June 5. .

6

54

1

24

24

12

20

1

3

June 6. .

4

36

15

2

3

8

12

3

6

3

June 7.. ..

1

9

20

16

4

17

12

5

7

7

June 9. .

5

41

14

16

15

8

6

4

June 15..

4

27

7

13

21

39

8

12

June 16.. ..

17

13

17

4

1

1

2

June 18 ...

12

76

13

37

16

2

3

1

June 21.. ..

16

7

22

1

June 22. . . .

3

3

4

1

June 25. .

1

June 28. .

1

1

Totals

Males

834

29

79

66

196

136

3

14

Females..

1683

17

23

134

145

106

3

11

1907.] WHITE-GRUBS AND MAY-BEETLES. 465

Our data show about thirty cases of oviposition by seven of our
species in our breeding-cages, ranging in date from the ist of June
to the middle of July.* As the beetles have begun to emerge more
than two months earlier, it is likely that they spend some time in
feeding before oviposition begins. In the Eighteenth Report of
this office it is said (p. 118) that the statement commonly made to
the effect that the eggs are laid in a ball of earth is clearly errone-
ous. This assertion must be corrected in the light of numerous ex-
periments made in my insectary in 1906 with May-beetles of several
species, all of which so deposited their eggs in the ground that each
was found inclosed within an earthen ball, a half inch in diameter,
probably formed by the extrusion with the egg of an adhesive fluid
which, upon hardening, held together the particles of earth which it
had penetrated. This method of inclosure was so general that eggs
were most easily found by sifting the dirt in breedi-ng-cages and
breaking open the spherical pellets of earth thus separated. The
eggs were laid at depths varying from not more than an inch to
five or six inches below the surface, the number for each female
varying from 44 for a specimen of L. inversa to 67 for L. implicita.
The following extract from the breeding-cage report of Mr. J.
J. Davis will give additional particulars of interest.

L. inversa. June 12, 1906, I female beetle in breeding-cage.
June 1 8, the earth examined and 44 eggs found, each in a ball of
earth from 3 to 3^2 inches below the surface. Eggs of a pure milky
color and of an oval shape, measuring i X X 2 mm. By the end of
three days they had swollen to a nearly spherical form, now measur-
ing 2 X 2}4 mm- Hatching first observed July n.

L. hirticula. Beetles collected and placed in breeding-cage June
19, 1906. No eggs were found till July 2, but July 9, 6 were found,
each in its ball of earth. The freshest eggs were white with a
glossy luster. They measured at first from il/2 X 2 mm. to 2 X 2^2
mm. Five days later these eggs had swollen to 2 mm. in diameter,
and were 2l/2 to 2^4 mm. in length.

L. ephelida. A single egg obtained August 4, 1905, from beetles
collected at Carbondale, 111., July 26, and placed in breeding-cage
in insectary July 29. This egg was comparatively small and defi-
nitely oval, measuring at first IJ/3X2 mm., and later 1^X2 mm.
L. ilicis. From beetles collected June 19, 1906, eggs were found
in oval balls of earth July 9, none having been present there on the
2d of that month. The eggs were a dull white, quite different from
the glossy luster of those of L. hirticula. They measured at first

*A specimen of L. ephelida, taken July 29, 1905, at Carbondale, in southern Illinois, laid
eggs until August 4.

466

BULLETIN No. 116.

[August,

i/^ X 2^2 to 23/4 mm., the shorter diameter later enlarging to

2 mm.

L. crcnulata. From a single female beetle placed in a breeding-
cage July 15, 1905, three eggs were obtained three days later,
deposited at a depth of about an inch. These eggs were oval, measur-
ing il/2 to 2l/2 mm. They were white when first laid, but changed
afterwards to cream color.

L. fusca. Eggs were obtained June 22, 1905, from beetles which
had been placed in a breeding-cage April 24. One of these eggs
hatched on me 27th of June.

L. implicita. Adults collected at Elliott, 111., from cells in the
earth, were placed in a breeding-cage in the insectary October 13,

1905. They were first seen out of their winter quarters April 28,

1906. June 12, 1906, 3 females were alive and 6 eggs were found
by sifting the dirt. On the 2oth of June only I beetle remained
alive, and this was a female. No more eggs were found up to June
25, but on the 5th of July 42 eggs were sifted out of the dirt, each
in its separate ball of earth. These were from 5^ to 6 inches below
the surface. Those most recently laid, measured 1 1/4 X 2 to 2^4 mm.,
while those which were longest deposited measured 2 X 2^2 rnm.

RELATIONS TO WEATHER.

The beetles of Lachno sterna transform from the pupa in summer
and fall, remaining, as a rule, in their underground cells, from 2 or

3 to 5 or 6 inches below the surface, unaffected, so far as. we know,
by any degree of cold to which they are likely to be subjected in our
climate. Their nocturnal movements after they come out of the
earth are, however, easily influenced by the weather. During thirty-
one nights, commencing May 14 and ending June 28, 1906, these
beetles were studied and collected at Urbana by Mr. West. On five
of these nights no beetles were seen or caught, although the fields,
the lights, and all the best feeding grounds were visited. The rec-
ords of minimum temperature for these five barren nights, and the
rate and direction of the wind, were as follows :

Date

Minimum Temperature

Rate and Direction of Wind
(Anemometer Record)

May 19

41° F.

N. E. 6 to 8 miles per hour

May 28

42° F.

N. E. 4 to 14 miles per hour

May 29

38° F.

S. E. 6 to 12 miles per hour

June 11

49° F.

N. E. 12 miles, all night

June 12

46° F.

N. E. 14 miles, all night

1907.] WHITE-GRUBS AND MAY-BEETLES. 467

No beetles were taken on any night when the thermometer regis-
tered below 52°, except May 21, when the temperature was 62° at
9 p. m. but fell to 46° before morning. A cold rain or high wind
kept them confined at night to their day-time hiding places, and they
were never abundant on their food plants, or flying freely, unless
the minimum temperature was at least 60°. They appeared in great-
est numbers on warm quiet nights following bright sunny days.
The beetles continue feeding during rain if a storm comes up during
a night favorable to their movements; and even their flights are
not wholly suppressed by moderate rain if the weather is warm.

MODES AND PLACES OF HIBERNATION.

Our common white-grubs hibernate, in the latitude of central
Illinois, in the two stages of larva and beetle, and in these stages
only. In fifty-seven collections, distributed over several years, ob-
tained by following the plow in fall and in spring, not a single pupa
of these species has occurred, although recently transformed beetles,
still inclosed in their pupal cells, have been collected by the hundred.
The pupa of Lachnosterna may possibly go through the winter now
and then, transforming the following spring, but this is certainly
an extraordinary occurrence in our latitude, quite insignificant as a
factor in the life history of the species. It is also a very unusual
thing for the beetles to come out of the ground in fall. Indeed,
those taken from the earth and placed in breeding-cages in either
fall or early spring, commonly bury themselves without delay. Now
and then a single specimen may be found active in fall, but we have
seen but one such case in the course of our several years' work. The
beetles are evidently more resistant to cold than the grubs, and do
not attempt, as a rule, to escape by going farther into the ground
with the approach of winter.

During the summer most of the grubs are near the surface of
the soil. A small percentage may be found to a depth of eight or
even ten inches, but the average is about three inches. In late fall
they begin to go down as a protection against the approaching win-
ter's cold, and may reach a depth of two to two and a half feet. In
October and November, 1905, the downward movement of the
grubs infesting a field of corn, part of which had been completely
destroyed by them, was followed by digging over, on each of five
days, several areas each three and a half feet square, and counting
the grubs exposed. The following table gives the dates at which
this search was made, the average number of grubs found for each
square of three and a half feet, the range in depth of the grubs dug
out, and the average depth for each date.

46$

BULLETIN No. 116.

[August,

Date

Average Grubs
per Square

/Range in Depth

Average Depth

Oct. 3, 1905. .

29.2

Near surface to 8 in.

3.5

Oct. 10, 19U5. .

22.6

Near surface to 10 in.

3.1

Oct. 23, 1905. .

25.3

Near surface to 10 in.

3.1

Oct. 31, 1905. .

22.

Near surface to 16 in.

6.4

Nov. 22, 1905. .

24.75

Three in. to 23 in.

10.

November 22, the last of the above dates, most of these grubs
were from 7 to 14 inches below the surface; but one was found only
3 inches down, seven had stopped at a depth of about 6 inches, and
three had gone to 20 to 23 inches below the surface. The ground
did not freeze permanently until several days after this date.

The grubs approach the surface in spring when the frost leaves
the ground and the soil becomes fit to plow, and one often sees in
the bottom of the furrow the tubular burrows made by them in
coming up from their winter quarters.

PRINCIPAL ENEMIES.

" Swine. — Pigs are by far the most destructive enemies of white-
grubs and of May-beetles. They are extremely fond of these insects,
and of all others within their reach which are large enough to at-
tract their attention, and the diligence with which they will tear in
pieces the sod of an infested pasture, and the depth to which they
will dig in pursuit of grubs in cultivated ground are matters of
common observation. They will also search out and destroy the
May-beetles in May and June if allowed to range over pastures and
meadows where these insects hide by day and to which they resort
to lay their eggs. Pigs are consequently our most useful agents for
the destruction of these insects — a point which will be more fully
discussed in this paper under "Measures of Prevention and Rem-
edy."

Crows and Blackbirds. — Next to pigs the most efficient destroy-
ers of white-grubs among our common larger animals are crows
and crow-blackbirds, both of which eat them greedily where they
can find them in sufficient numbers to make them an important ar-
ticle of food. Evidence on this point is less positive with respect to
crows than concerning blackbirds. Mr. W. B. Burrows, of the U. S.
Department of Agriculture, who has studied the food of the com-
mon American crow by examining the contents of more than a
thousand stomachs, reports that he has found white-grubs in a com-
paratively small number of these stomachs, but that May-beetles had
been eaten by very nearly all the crows taken at a time when these

1W7.] WHITE-GRUBS AND MAY -BEETLES. 469

insects were abundant in the beetle stage, making, indeed, the greater
part of the insect food of all the crows collected at that time.

To these well-known facts I have to add two significant items of
observation reported to me by my field assistants. One of these,
Mr. E. O. G. Kelly, who was engaged during much of the season
of 1906 in a field study of injuries by white-grubs, unusually serious
that year in central Illinois, tells me that he often saw considerable
numbers of crows following after the plow in fall, evidently picking
up white-grubs, and that he has also seen flocks 9$ crows alight in
a badly infested pasture and tear the sod in pieces in search of the
grubs, fighting with each other for their possession when thus ex-
posed. Another assistant, Mr. A. O. Gross, employed last fall in
collecting data for a census of the bird life of Illinois, found, in a
trip across the state made on foot in September and October, that
next to the horned lark, crows were the most abundant birds on
plowed ground, averaging seventy-nine per square mile in all the
recently plowed fields crossed on that trip. They could have had no
other object there than the search for insect food.*

In a study of the food of blackbirds, made by Mr. F. E. L. Beal
for the U. S. Department of Agriculture in 1894, it was found that
these birds ate either beetles or grubs in every month from March
to October inclusive. In May these insects made more than a sixth,
and in June one ninth, of the entire food. Many stomachs were
found to be literally crammed with grubs ; and in many more, grubs
had formed a large part of the previous meal.

The Common Grub Wasp (Tiphia}. — Much the most important
insect enemy of the white-grubs is a wasplike insect belonging to the
hymenopterous genus Tiphia. It is a slender, jet-black species, usu-
ally about two thirds of an inch long, but sometimes smaller, and
with wings either clear or more or less deeply tinged with dusky
yellow. It enters the ground in search of the grubs, follows them
up in their burrows, and lays on the back of each grub a single egg,
which hatches in a little over a week into a footless, maggot-like
larva. This larva adheres to the surface of the insect, punctures its
skin and sucks its blood for a time, but finally eats it up. The Tiphia
larva then spins, under ground, an oval brown coccoon within which
it goes through its transformations, coming out as a winged insect
the following summer. The rate of multiplication of the species
is not known, but it is certainly sufficient to enable the Tiphia vir-
tually to destroy, under favorable circumstances, the entire grub
population of a badly infested field.

*" An Ornithological Cross-section of Illinois in Autumn.'' By S. A. Forbes. Bull. 111.
State Lab. Nat. Hist., Vol. VII., Art. IX., p. 318.

470 BULLETIN No. 116. [Auyust,

The method of the operations of this insect and the main facts
of .its life history have been worked out in my insectary during the
past two years by Mr. J. J. Davis and Mr. J. A. West from coccoons
and infested grubs sent in by Mr. Kelly from fields at Elliott, 111.
Thirty-three Tiphia cocoons were used in these observations, twenty-
one of which were obtained November 25, 1905, and twelve April
27, 1906. From those collected .in fall the winged insect emerged
at thirteen dates between June 19 and July 28, 1906, and those ob-
tained in spring yielded the adult on eleven dates between June 26
and August 22. These collections consequently do not represent dif-
ferent broods. - Only seven of the adults obtained were males, and
twenty-five were females, the sex of one being undetermined.

A pair were seen in copula in one of the breeding-cages at 9 130
p. m. July i, and eggs were laid on grubs in the insectary from June
29 to August 21. One lot of young white-grubs brought in Sep-
tember 20, 1906, were already badly infested by very small Tiphia
larvae about one eighth of an inch in length. As insectary observa-
tions show that the eggs hatch in from seven to ten days, and that
the young larva reaches the length of an eighth of an inch in about a
week, it appears that the eggs for these larvae were laid a little later
than September i. The period of oviposition of this grub wasp is
thus something more than two months.

In several cases a female Tiphia was induced to go through the
whole operation of preparing her victim and depositing her egg
upon it above ground in a breeding-cage, where she could be con-
tinuously watched, and the facts thus learned are unusually inter-
esting. Like others of its family — the digger-wasps, or Scoliidce —
these insects sting their prey before attaching the egg to it, with the
effect to paralyze it more or less completely. Mounting the body of
the grub, which struggles violently against the attack, the Tiphia
seizes with her mandibles the skin- of the back just behind the head,
curving her body downward around the side of the grub, with the tip
of her abdomen beneath and just behind the head, and then, after feel-
ing about with the abdomen for a time, finally stings her victim, with
the effect suddenly to quiet its struggles and reduce it to helpless-
ness. Then the Tiphia reverses her position and works the tip of her
abdomen backward and forward for several minutes in one of the
grooves or creases on the back of the larva, usually not far behind the
head, apparently smearing the surface there with a viscid fluid, after
which she deposits her egg on this sticky surface and goes away.*

*The above account is based on insectary observations and experiments. Several white-
grubs parasitized by Tiphia larva have been found in the field since this was written, and in
every case the larva was on the under side of the body between the thoracic leg's.

1907.] WHITE-GRUBS AND MAY-BEETLES. 471

The larva, at first almost completely paralyzed by the puncture
of the sting and the venom doubtless injected at the same time,
slowly revives, recovering presently its full powers of locomotion,
so that it is indistinguishable by its behavior from its fellows which
have not been stung. The stinging, in this case, is thus a means of
quieting the struggles of the grub in a way to permit the. Tiphia to
attach her egg to its back. Commonly, of course, these operations
go on under ground. A Tiphia introduced into a breeding-cage con-
taining grubs in the earth disappears under ground herself, and does
not come out until she has found and infested a grub.

Repeatedly, where grubs were exposed to attack on the surface
of the dirt in breeding-cages, the Tiphia merely stung them at first,
and then proceeded to bury them before depositing her egg. For
this purpose, she undermined the grub by digging the earth from
beneath it, pulling its body about by means of her jaws until it was
in proper position to enter the hole, gradually digging deeper, and
finally burying it completely. In one case in which the operation
was timed, the grub was buried in ten minutes after it was stung.
Sometimes the Tiphia abandoned an attempt at burial, and left the
grub without placing an egg on it after it was stung.

Apart from that general exhibition of a wonderful adaptation
of its actions to the needs of its prospective progeny which this Ti-
phia shares with many other wasps, and especially with those of its
own family, there are two points of peculiar interest in this account
It is an unmistakable fact that the effect of the poisoning of the
grubs by the Tiphia is merely to paralyze the victim temporarily ; to
overcome its resistance and reduce it to helplessness while the Tiphia
egg is being placed in position. The sting is used as a mere aid in
the struggle of the Tiphia with a stronger insect. This fact may
point to the explanation of the origin of the remarkable instinct of
the solitary wasps to sting and paralyze their prey.

More remarkable still, however, in the light of our present
knowledge of the habits of Tiphia, is its frequent burial of white-
grubs exposed to it on the surface of the ground. Since digger-
wasps in general are parasites of underground larvae only, since the
Tiphia is not known to infest any insects except white-grubs of the
genus Lachnosterna, and since in nature it can never find these
grubs above ground, 'its deliberate burial of exposed grubs has all
the appearance of a line of action extemporized to meet a previously
unknown condition. Either the Tiphia, disturbed at finding its prey
exposed, buries this as a result of impulse aided by intelligent con-
trivance, or we shall find, when its habits are known in full, that it

472 BULLETIN No. 116. [August,

does sometimes normally infest and attack insects exposed above
ground by their habits, burying them as a matter of instinct after
it has placed its egg. Tiphia has not, in fact, been studied as an in-
dependent species, but all the data concerning its habits and life
history have been gathered in the course of studies of the white-
grubs.

The egg of Tiphia remains firmly glued to the back of the chosen
grub, and hatches in seven to ten days. The young larva breaks its
way out from the egg at one end, and, although it begins at once to
feed, it does not at first free itself from the shell, but as it grows
this finally splits and breaks away. When it first emerges the larva
measures slightly more than a millimeter in length. From our scanty
data it appears that it takes about two weeks to get its full growth,
and that it doubles its size in the last two days of its larval life, dur-
ing which it is engaged in devouring the body of its host. Previous
to this time it has been adherent to the skin of the grub whose fluids
it has lived upon. When full grown it is from two thirds to four
fifths of an inch in length.

The cocoons are cylindrical ovate, from 17-22 mm. long, clay-
colored at first, and wood-brown or cinnamon-brown when older.
From our observations thus far made it appears that the larva
hibernates within the cocoon, not pupating until the following
spring. The adult emerges from a little one side of the larger end,
in which it leaves a ragged and irregular opening. In several cases
the abundance of these conspicuous brown cocoons in the earth was
such as to indicate an enormous destruction of white-grubs, and
there is no doubt that this parasite is an important agent in checking
destructive uprisings of these insects.

That this wasp, parasitic on white-grubs, is itself parasitized, is
shown by the results of observations made on Tiphia cocoons col-
lected April 27, 1906, and kept in breeding-cages during the sum-
mer. From these emerged, July 7, 16, and 31, adult bee-flies (Bom-
byliidce) of the species Exoprosopa fascipennis, each freeing itself
from the Tiphia cocoon by cutting out a circular piece at the larger
end. The eggs from which these flies resulted were probably laid
on the Tiphia grub in 1905, before the cocoon was spun.

MISCELLANEOUS INSECT ENEMIES.

Macrophthalma disjuncta. — This little tachinid fly was men-
tioned in my Seventh Report as bred repeatedly from dead white-
grubs, but I was nevertheless uncertain that it was a parasite. Lately
its parasitic nature has been proven by repeatedly breeding it from

1907.] WHITE-GRUBS AND MAY- BEETLES. 473

living grubs kept in breeding-cages in my insectary. Adults have
emerged in these experiments March 26, June 8, July 12, and Au-
gust 8, and others have been taken at electric lights July 9, and in a
corn field September 27. Those appearing March 26 lived in con-
finement until May 14. We have thus seen these insects alive in
every month from March to September inclusive. In the breeding-
cages, remains of a white-grub were commonly found "associated
with the cocoon of the parasite.

The adult of this species is a large blackish-gray fly with a gen-
eral resemblance to the common large blow-fly, but with a grayish
white sheen on the basal half of each segment of the abdomen, giv-
ing the effect of equal alternating cross-bands of black and gray.

Ophion bifoveolatum Brulle. — This well-known parasite of the
white-grub has been reared by us several times from these insects.
In one case the head and skin of a grub were woven into the wall of
the cocoon of the parasite. The species has been bred by us repeat-
edly from cocoons collected from the latter part of July to the first
of September, and kept in breeding-cages through the winter, adults
appearing from March 3 1 to April 27.

The adult is a large, slender-bodied, dark red ichneumon-fly;
and the cocoon is quite regularly elliptical, a half inch long by a
fourth of an inch thick at the middle, smooth, dull brownish, or
more or less blackish — especially towards the end.

Sparnopolius fulvus Wied. — This bee-fly, which we have some-
times noticed in corn fields and have collected from miscellaneous
sweepings of vegetation in midsummer, also proves to be a parasite
of the white-grub, as shown by breeding-cage work done in 1904 —
1906. It was first detected in this relation by Mr. E. P. -Taylor, of
my office, who found a white-grub at Elliott, 111., August 25, 1904,
with a dipterous larva attached to its back. This was placed in an
insectary cage, which was not examined until April 21, at which
time the white-grub -had been completely destroyed, and the larva
had completed its transformations. It probably had emerged in the
fall of 1904. A larva of this same species was next collected July
24, 1906, from among corn roots at Effingham, 111., and was placed
in a breeding-cage to obtain the adult. It pupated August 22, and
emerged as a winged insect September 10. All our open-air collec-
tions of this fly have been obtained in August.

The adult is about as large as a common house-fly, but is covered
with erect yellow fur. The pupa is not inclosed in the last larval
skin. Its head bears three large points on each side anteriorly, and
a smaller pair beneath at the base of the mouth-parts. The last seg-

474 BULLETIN No. 116. [August,

ment of the pupa is rather narrowly truncate, with a small slender
spine on each side of the truncation, and a shorter one beneath each
of these.

Considerable numbers of another species of parasitic larva were
taken by Mr. Kelly at Elliott, 111., August 29 and September 20,

1906. These were evidently white-grub parasites, as the remains of
the grubs'were still clinging to several of them. This species is still
in the larval stage at this writing.

Three yellow coarcate meloid larvae were also found by the same
assistant in an infested oats field with the remnants of white-grubs
attached to them, and another was taken in a similar condition Oc-
tober 10. These specimens have not yet matured.

Pyrgota undata Wied. — One of the most interesting parasitic
enemies of the white-grubs is a large, rather unusual-looking fly of
the family Ortalidce, noticed by, Mr. J. A. West, an assistant of my
office, as abundant among the beetles at night. Now and then May-
beetles were seen to drop to the earth, trying to rid themselves of the
adult flies which were clinging to their backs, each with the last
segment of the abdomen thrust in between the wings and wing-
covers of the beetle and firmly held in place over the middle of the
abdomen. The flies were apparently thus thrusting their eggs into
the backs of the beetles through the thin dorsal skin beneath the
wing-covers. The tip of the abdomen of the female fly is admirably
adapted to this object, being hard and subconical, and directed down-
wards at a right angle to the axis of the body.

The relations of these insects were experimentally determined
by confining, June 9, 1906, adult May-beetles in a breeding-cage
with several of the flies. These would light on the backs of the
feeding beetles, which would at once drop to the ground with the
flies clinging to them. Whenever a beetle spread its wings for flight
the insect on its back inserted the tip of its abdomen between the
May-beetle's wings, evidently depositing an egg in its back. Beetles
so treated lived for some days, and then began to die. On the 2/th
of June, five of the beetles were dead, and in the bodies of two of
these, dipterous maggots were found. July 10, three of the beetles
contained each a dipterous puparium, which remained unchanged
until May of this year, when all produced adults of P. undata. Au-
gust 29 and September 20, 1906, several puparia were found in the
bodies of dead May-beetles, and these, kept in breeding-cages
through the winter, produced adults of P. undata May 14 and 17,

1907. Like experiments begun during the present year have pro-
gressed similarly to the time of writing. Adult flies of this species

1907.] WHITE-GRUBS AND MAY-BEETLES. 475

were again frequently seen June 12 to 18, 1907, among May-beetles
on trees at night, no less than twenty-six specimens being captured.
These flies have also been occasionally taken at electric lights, and
in various situations by day during different years, from May 20
to June 17.

The puparia of these parasites are dull black, broad ovate, widest
at the posterior third. At the tip is a small shallow excavation en-
circled by a rugose ridge, which is elevated latero-dorsally into a
pair of short irregular tubercles, the tips of which are about a milli-
meter apart. Length 7-8 mm. ; greatest diameter, 4.5-4.8 mm. ;
diameter of anterior end, about 3 mm. The adult flies are yellow-
brown, three eighths to half an inch long. The head is subtriangular,
the thorax globose, the abdomen slender at base, enlarging apically.
The wings are three eighths to half an inch long, conspicuously and
characteristically marked. The entire anterior margin of the wings
has a broad brown border reaching half way across the wing, and
having two broad saw-tooth-like extensions attaining the posterior
margin, one at the middle of the apical half and the other at that
of the basal half. The first two abdominal segments are about as
long as broad, and connate; the next four, in the female, are very
short, followed by the genital segment, which is very large, shining,
directed downwards and curved slightly forwards.

The male abdomen is similarly shaped : the two basal segments
are followed by two more about twice as long as the corresponding
ones in the female ; the next segment is a little longer than broad,
vertically directed, bearing the genital segment, which is directed
somewhat anteriorly. The eyes are larger in the female than in
the male.

Other Dipterous Parasites. — In 1905 a May-beetle of the species
Lachno sterna crenulata found near Urbana July 15, laid three eggs,
and died about the 29th of July. On August 5 an adult tachinid
emerged from the body which Mr. Tyler Townsend, of the U. S.
National Museum, regards as a new species — Viviana. Two dip-
terous larvae were found June 27, 1906, in a May-beetle taken alive
May 31. July 10 these larvae had formed puparia, and adult tachinid
flies emerged May 17 and 18 of the following year. These are
slightly larger than a house-fly, with black subquadrate thorax, the
anterior angles each with a triangular red spot. The puparium is
very dark red, almost black, subcylindrical, with rounded ends.
Length, 7 mm. ; width, 3 mm. It is smoothly rounded behind, with
a pair of low tubercles placed close together. The species has not
been determined.

476 BULLETIN No. 116. [August,

RELATION TO SOIL AND SUBSOIL.

It is a matter of common opinion that injuries by white-grubs
are more serious on the higher, lighter, and drier parts of our culti-
vated areas than on the lower and moister parts, but no exact ob-
sevations have been made to show whether this apparent difference
is real under all conditions, and whether, if so, it is due to a greater
abundance of the grubs on high lands than on low, or to a lesser
average power of recuperation and resistance on the part of plants
growing in comparatively light and less fertile soils.

I began in 1904 and 1905 to accumulate data on this and allied
points, by having collections of white-grubs made by persons follow-
ing the plow, who recorded for each field and situation the number
of grubs found in each quarter of a mile of furrow. A record was
also made, for each field examined, of the succession of crops it had
borne for the five years preceding, of the character of the soil, the
lay of the land, the conditions as to drainage and to fertilization,
and the relation of the field to trees and shrubs on which the parent
beetles of the grubs might have found food. Collections were made
on this plan from seventy-nine fields in the following twelve counties
of central and southern Illinois: Stark, Peoria, Woodford, Mc-
Lean, Champaign, Macon, Macoupin, St. Clair, Washington, Ma-
rion, Jackson, and Union. This work was interrupted by lack of
funds and by diversion of assistants to more pressing problems
before any sufficient mass of data had been obtained to enable me
to draw satisfactory general conclusions on any one of the points of
principal interest. So far as they go, they show that the grubs were
more abundant on the higher and drier parts of the country than on
the lower and moister parts, and that the fewest eggs were laid by
the parent beetles in corn fields and the most in grass-lands. Thirty-
eight low-land fields gave an average of 21 grubs exposed in a mile
of plowed furrow, and 41 of the high-land fields an average of 31 to
the mile. The three largest numbers found in any fields were 208,
164, and 140 grubs to the mile, all on high ground. The largest num-
bers in any of the low-land fields were 112 and 104 in two of them.
Again, the average of fields which had been in corn continuously for
at least three years preceding was 17 grubs exposed in each mile of
furrow, and that of fields which, although in corn at the time, had
been in grass for several years preceding, was 37 grubs to the mile.
It is evident that useful information may be obtained from data of
this description if they are accumulated in sufficient number and are
properly classified.

1907.1 WHITE-GRUBS AND MAY-BEETLES. 477

RELATIONS TO AGRICULTURAL MANAGEMENT.

Injuries by white-grubs are influenced to a considerable extent
by the system of farming, and especially by the succession of crops ;
by the management of pasture-lands, in which, if left wholly to
themselves, they are likely to accumulate in increasing numbers year
by year ; and possibly, also, by the time of the year when infested
lands are plowed. While the old idea that white-grubs are essen-
tially insects of pastures and meadows has been exploded by ob-
servations of recent years, it still remains true that, other things
being equal, they are most abundant in grass-lands, and consequently
most injurious to other crops if these follow within one or two
years upon an infested pasture or meadow. They seem particularly
liable to accumulate in an old turf which has lain unbroken for sev-
eral years, and are less likely to be destructive where there is a quick
rotation of crops, including a short period in grass, to be followed
by one or two years in clover. The modern stockman's practice of
herding cattle and pigs together is an excellent one from our stand-
point, since the'pigs, in following the cattle, are likely also to search
out the grubs in the turf and to keep the sod practically free from
them.

It is a matter of common, though not universal, opinion among
farmers who have watched the work of the white-grubs that fall
plowing of infested lands is preferable to spring plowing. In the
absence of any apparent reason why this should be so, and in the
absence also of any experiments upon the subject and of any consid-
erable number of exact observations, this supposition must be re-
garded as doubtful. Our own field reports give thus far but a single
instance, reported by Mr. Kelly in 1905, of a notable difference in
white-grub injury corresponding to a difference in the time of plow-
ing of different parts of the same field ; and this instance is by no
means clear, since there was injury by grubs in both parts of this
field — much greater and more extensive, however, on the spring
plowing. The white-grubs were also reported as less abundant in
the part of the field plowed in fall, averaging there one grub to the
hill of corn as compared with seven to the hill found in the part
plowed in spring. The data of this observation are incomplete, how-
ever, and this difference in number of grubs may have been due to
something else than difference in the time of plowing.

INJURIES TO CROPS.

Injuries to crops by white-grubs and May-beetles are often of the
most serious and extensive character. The beetles by their destruc-

478 BULLETIN No. 116. [August,

tion of leaves of trees and shrubs in spring not infrequently cause
the death of those preferred by them for food, and the grubs are
particularly destructive in towns to the turf of lawns, in nurseries to
young evergreens, in the fruit plantations to strawberry vines, and
on the general farm to grass and corn.

The injury by grubs is due, in all cases, to the destruction of the
roots of the plants infested and the consequent weakening or actual
killing of the plant. The nature and extent of the injury to corn is
well illustrated by observations made by one of my assistants, Mr.
Kelly, in a field near Ludlow, in Champaign county, about ten acres
of which were almost completely destroyed. By digging up to a
depth of twenty inches, and searching all the soil belonging to each
of sixty hills of corn — an area, that is, three and a half feet square
for each hill — it was found that this badly injured area contained
an average of 3,460 grubs to the hundred hills, or more than 34 to
the hill,1 — a total of about three hundred pounds of grubs to the acre
of corn. The plants varied in height from two inches to six feet,
and the total number of ears borne by two thousand hills was 786,
all small ears or nubbins.

PREVENTION AND REMEDY.

The subject of preventive and remedial measures was somewhat
fully treated in my Seventh Report (pp. 127-137), and there is
nothing important to add to that discussion at the present time be-
yond a statement of the results of an experiment with pigs as a
means of clearing the grubs out of an infested field. This experi-
ment was made in the field above referred to, near Ludlow, 111., ten
acres of the worst injured part being surrounded with a temporary
fence, and one hundred pigs averaging seventy-five pounds each,
together with eight large sows, being turned into the inclosure Sep-
tember 23.

By October 13 the pigs had rooted over the whole surface of
the ten-acre lot, going, in some places, to a depth of ten or twelve
inches. An area equivalent to twenty corn hills was now examined
to a depth of twenty inches, with the result that an average of 4.8
grubs per hill were found, as compared with 34.6 per hill at the
beginning of the experiment — a benefit of 86 per cent, in twenty
days. The grubs found in the field at this time were usually eight
inches or more below the surface.

The pigs were in this inclosure until October 20, when they were
removed to another badly injured part of the field, and a final ex-
amination of the plot was made. In an area equal to ten hills of

1907.} WHITE-GRUBS AND MAY-BEETLES. 479

corn only two grubs were found — a benefit of over 99 per cent, de-
stroyed by the pigs in twenty-seven days. As the grubs were at this
season going down to escape frost, the hogs were burrowing in
pursuit of them, sometimes to a depth of two feet.

Although these pigs remained perfectly thrifty, it is proper to
say that there is one possibly serious objection to this very common
use of swine as a means of keeping in check the white-grub; in grass-
land and of clearing them out of fields of corn. It has been shown
by Dr. C. W. Stiles, of the U. S. Bureau of Animal Industry,* that
one of the most injurious intestinal parasites of swine, known as
the giant thorn-headed worm (Echinorhynchus gigas), passes one
stage of its life in certain of the white-grubs, and that pigs become
infested by it by devouring infested grubs, which themselves obtain
it by way of the excrement of the pigs. Where either grubs or pigs
become infested by these parasites the situation is more or less dan-
gerous if pigs are allowed to eat the grubs; but pigs which have
never been pastured are certain to be free from these parasites, and
grubs growing in fields which have not been pastured by pigs are
likewise certain to be free from them. The use of such pigs upon
such fields would consequently be without danger from this source,
and a little attention to these facts will avoid any injurious conse-
quences. That is, if pigs not previously allowed to run out are
turned into fields on which pigs have not been pastured within three
years, there will be no danger that they will become infested by
these thorn-headed worms.

The general measures discussed in my Seventh Report are es-
sentially a destruction of the May-beetles before they have laid their
eggs, and the distribution among the grubs of the germs of their
contagious diseases. Nothing has thus far been done to test the pos-
sibility of the collection and distribution of parasites other than
those of contagious diseases, and the latter subject can not by any
means be said to have been worked out to final conclusions.

The May-beetles may be destroyed either by spraying repeatedly
with arsenical poisons the trees on whose foliage they feed; by
shaking or jarring them down in the cooler parts of the night from
the trees and shrubs on which they are feeding, and collecting them
for destruction ; and by trapping and killing them at night by means
of lanterns fastened over tubs or traps containing water covered
with a film of kerosene. The grubs may possibly be kept in check
by the distribution among them of the germs of their contagious dis-
eases obtained by artificial cultivation, — a method which has been

*"On an American Intermediate Host of Echinorhynchus sigas." By C. W. Stiles Zool.
An?., Feb., 1892, p 52.

480 BULLETIN No. 116. [August, 1907.

used with some success against the white-grubs of France. The
main dependence in the Old World, however, has been a thoroughly
organized movement for the collection of the beetles from the trees
at night, the usual method of securing general action being to pay a
sufficient price for the beetles in quantity to make their collection a
profitable enterprise during the time of their presence on the trees.
This method can be used to.advantage only by owners of very large
estates or by communities or combinations of farmers acting to-
gether for their common benefit. The same may be said of the
destruction of the beetles by poisoning their food. If the ordinary
land owner were to proceed by himself, it is probable that his fields
would become infested by invasion from without even though he
might destroy every May-beetle on his own premises. The least
promising of these methods is the simplest and the cheapest of them
all — that of collecting the beetles by lantern traps. These take ef-
fect much the most strongly upon the males, and collect, under the
most favorable circumstances, only a comparatively small percentage
of the beetles in their neighborhood. Furthermore, it is available
only on dark and relatively quiet nights.

What may be done by way of general concerted action is well
illustrated by a campaign of destruction carried on against the white-
grubs of the Swedish province of Halland during the ten years from
1885 to 1895, within which time 29,736 bushels of May-beetles and
their larvae were collected at an expense of $15,554, or about 52
cents a bushel, the state usually paying half of this sum, the Eco-
nomic Society of the province a fourth, and the communes or coun-
ties the remaining fourth. The effect was especially shown in the
gradual reduction in the number of beetles collected — from 14,-
801 bushels in 1887 to 5,611 in 1895, although the number of com-
munes participating in the work had increased in the meantime, and
the area covered by the collections was correspondingly greater.*

So far as is now to be foreseen, organized work of some such de-
scription will finally be necessary to the control of the white-grub
pest in Illinois, and throughout America generally.

*Aug-ust Lyttkins, in Entomologlsk Tidskrift for 1897. Stockholm, 1898.

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